1. Field of the Invention
The present invention is related to a connector assembly with multiple rows and columns of conductive elements, especially to a connector assembly having a plurality of inner circuit boards mounted therein to form needed conductive paths to connect with a daughtercard and a backplane assembly.
2. Description of the Related Art
A backplane assembly includes a primary circuit board with connectors mounted thereon to enable servers/workstations to bring multiple network modules together and harness them to interoperation. Electrical connectors for interconnecting a primary circuit board of the backplane assembly to daughterboards generally comprise two mating connector halves each having multiple rows and columns of conductive elements or contacts. The backplane to daughterboard mating connector halves have a high conductive element/contact density and are required to operate at relatively high electrical speeds. It is known to provide each column of contacts as a separate module that includes a vertical array of contacts having an overmolded carrier. Multiple modules then are installed in a connector housing to form a complete connector. U.S. Pat. Nos. 5,066,236 and 5,664,968 both show such a connector structure. Generally, all of the modules in such a connector are substantially identical. But different types of modules sometimes are needed in a connector in order to accommodate different electrical characteristics of signals through the connector. Besides, due to continuing trends toward miniaturization and improved electrical performance -by the electronics industry, requirements for greater conductive element/contact density and higher electrical speeds are constantly being promulgated. These requirements lead to design conflicts, especially when electrical speeds are in the range of approximately 500 megahertz and above, due to the fact that increasing the contact density places the conductive elements/contacts in closer proximity to each other, thereby leading to crosstalk between neighboring conductive elements/contacts in different signal pairs. Thus, as introduced in U.S. Pat. Nos. 5,104,341 and 6,299,484, some ground reference means are disposed between every two signal modules to reduce crosstalk therebetween.
However, new overmolded technology developing recently shows possibly high production cost may be caused because more and more minimized conductive elements should be assembled together in a small-sized plastic block. It is much difficult to position these high density arranged conductive elements in a overmolding mold due to the high plastic injection pressure and scarce space between these elements. A precise and complicate mold that usually costs high is needed to achieve the production. Therefore, some other substitutes like a circuit board are considered. Robin et al. U.S. Pat. No. 4,571,014 and Paagman U.S. Pat. No. 5,924,899 both show a plurality of inner circuit boards installed inside a backplane connector. Each conductive path on these circuit boards can be thinner and closer to each other than a separate stamping contact of the overmolded module though a perfect small circuit board costs high too. However, an extra solder tail or a mating contact for every conductive path on the circuit board is needed and most of them should be soldered onto the circuit board first before the circuit board is installed into the backplane connector. And the solder joints of every circuit board may be hurt or broken when the backplane connector is mated because the mating force applied on every circuit board can be transferred to its solder joints right away. More fixing or positioning features have to be adopted to overcome this situation and result in a higher product cost.
Therefore, an object of the present invention is to provide an electrical connector used in a backplane application with inner circuit boards installed therein to achieve a better electrical performance by using a separable and removable connection between the inner circuit boards and other conductors inside the connector.
Another object of the present invention is to provide an electrical connector having larger tolerance to undesired mating displacement of inner circuit boards installed therein and maintaining better electrical performance in a vibration circumstance.
Another object of the present invention is to provide an electrical connector having inner circuit boards which can be replaceable or repairable after the connector is mounted onto a printed circuit board in a simple process without reflow or dismantling the whole connector from the printed circuit board.
Another object of the present invention is to provide an electrical connector having alternately arranged signal and ground transmission path to keep all the signal conductors being surrounded by grounding means throughout the connector and establishing better ground reference neighboring these signal conductors for reducing effectively undesired crosstalk between them.
Another object of the present invention is to provide a connector assembly used in a backplane application having a receptacle connector and its complementary header connector both using mostly identical conductor parts to engage with inner circuit boards installed within the receptacle connector to facilitate the production of both connectors and their assembling process.
To obtain the above objects, an electrical connector in accordance with the present invention includes a top housing and a bottom housing to form a receiving space therebetween. A plurality of parallel partitions extends respectively from the inner face of the top and bottom housing and protruding into the receiving space. Inner circuit boards with traces thereon are respectively inserted and stay in the space between every two partitions of either the top housing or the bottom housing.
Specifically, pairs of signal contacts and grounding plates are installed in the bottom housing. The signal contact pairs are respectively received inside every partition in one row and exposed their engaging arms out of one surface of the partition while each grounding plate is seated and abutting against the other surface of every partition respectively. Meanwhile, each of the inner circuit boards has pairs of signal traces on one surface and a grounding layer formed on the other. So the conductors installed inside the connector include signal transmission pairs and ground means disposed alternately with the signal transmission pair rows throughout the connector though the connector comprises two separate and mating conductors installed therein. Therefore, in high-speed transmission application, the ground means next to every signal transmission pair can provide a better and more effective coupling or ground reference to reduce undesired crosstalk generated therebetween.
Furthermore, due to the separable engagement between the inner circuit boards mostly received in the top housing and the conductors, pairs of signal contacts and grounding plates, received in the bottom housing and the fact of the top housing being removably latched above the bottom housing, the inner circuit boards can be dismantled and replaced anytime even though the connector is mounted on a printed circuit board and no special treatment or process like reflow is needed.
Besides, compressible ridges are disposed on the inner top face of the top housing between every two partitions in spaced-apart relationship. And holes are formed on the top housing and the bottom housing respectively and can be treated as a pair because each hole on the top housing and its related one on the bottom housing are located in the same plane right between two spaced-apart partitions. Two projections corresponding to the holes extend out of edges of every inner circuit board and are inserted in the holes when the connector is assembled. Meanwhile, a plurality of stops abutting against the inner bottom face of the bottom housing is stamped out of the surface of each grounding plate. Every one of the inner circuit board is rested on the top of the stops of a corresponding grounding plate and is pressed by the compressible ridges of the top housing in order to be positioned when the connector is assembled. Therefore, the inner circuit boards can be held in position inside the connector though they are not actually fixed therein. The effective engagement between the boards and conductors in the bottom housing will be continuously maintained by holes of the housings and a flexible mechanism like ridges cooperating with stops of grounding plates when the connector is mated with its complementary connector.
Furthermore, the complementary connector in accordance with the present invention has a housing with similar partition arrangement to the bottom housing of the receptacle connector. Same conductors, including grounding plates and signal contacts used in the bottom housing of the receptacle connector can be adopted again for the same purpose of mating with edges of the inner circuit boards. So the producing cost of the connector assembly can be reduced efficiently.
In addition, on each inner circuit board, signal traces have pads at their both ends for the mating use. Some of the pads have a cut-off area near the mating edge of the inner circuit board in order to keep coincident impedance along the traces when the traces are used to transmit signals. Thus, a better electrical performance can be achieved by the inner circuit board in the high-speed transmission application.
Furthermore, each signal contact used in the bottom housing of the receptacle connector and the complementary connector comprises an flexible engaging arm and tail portion at its two distal ends respectively. And each grounding plate has a plurality of press-fit tails extending therefrom. When the receptacle or complementary connector is mounted on a printed circuit board, the press-fit tails of grounding plates are pressed into the corresponding holes on the printed circuit board to fix the connector and the tail portion of the signal contact can be compressibly engaged on the printed circuit board with a solderless process at the same time. The mounting process of the connectors is simplified and time-saving.
Besides, each grounding plate abutting against a partition of the connector has several flexible beams extending to the other side of the partition, and lanced arms punched out from the grounding plate located next to the surface of the partition. Both of the flexible beam and lanced arms can be engaged with the different inner circuit boards next to the grounding plate and establish more ground conductive path for every inner circuit board. The better coupling and ground reference effect for high-speed signal transmitted by signal contacts next to the grounding plate will be achieved and the whole performance of the connector can be improved.
Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.